1. Field of the Invention
The present invention relates to a device for preventing liquid hammer. More particularly, the present invention relates to a device for preventing water hammer or fluid hammer which may occur inside a water pipe, or in a fluid channel of a hydraulic apparatus or other water related apparatus.
2. Description of the Related Art
There have been several types of liquid hammer prevention device (arrestor) in conventional and popular style, for example known as xe2x80x9cwater hammer arrestor,xe2x80x9d which effectively reduce liquid hammer occurring in a fluid channel such as inside a water pipe. The conventional liquid hammer prevention device may be roughly classified into two types, that is, an external attachment type connected at any intermediate position of the fluid channel, and a built-in type incorporated in an operation handle or the like which controls open/close of the fluid channel.
Further, the conventional liquid hammer prevention device may also be classified into other two groups, that is, an outer flange type in which an outer rim of a diaphragm is supported by an outer flange, and an inner flange type in which an outer rim of a diaphragm is supported by an inner flange. The fundamental structure of outer flange type of liquid hammer prevention device mentioned above, serving to effectively absorb and reduce the liquid hammer, is illustrated in FIG. 26. There is a cylindrical form of elastic cushion K of which outer diameter D and height H are substantially identical with each other, incorporated in a casing K0 of a liquid hammer prevention device 700. There is a hat-shape of diaphragm C comprising a stretch portion C1 and an outer rim C2, positioned at the exposed surface (i.e. not the surface being in touch with the casing K0) of the elastic cushion K. The outer rim C2 is in contact with the upper surface of a flange C3 and pressed down by the outer flange of the casing K0 by means of caulking at around the caulking means 725, thus the elastic cushion K is sealed. Further, the elastic cushion K incorporated in the casing K0 is attached to a pipe P1 via a mounting screw portion C4 of the flange C3. As illustrated in FIG. 27, the diaphragm C is a hat-shape diaphragm having the stretch portion C1 so that the stretch portion C1 may follow the displacement of the elastic cushion K by a considerable large amount of L in the direction of the height H thereof, which occurs when the elastic cushion K receives a liquid hammer force P through a passage hole 701 and a certain volume of buffer space.
The reason for adopting the cylindrical shape for the liquid hammer prevention device 700 as above discussed is to secure more than a predetermined volume of the elastic cushion K in order to effectively serve the liquid hammer absorption function. To satisfy this requirement, it is necessary to provide the elastic cushion K with a predetermined hardness, and with the height allowing the compression displacement by a predetermined amount. In addition, since the liquid hammer prevention device 700 is in the cylindrical shape, the diaphragm C of the elastic cushion K may have the durability in order to prevent the exposed surface of the elastic cushion K from being hollowed due to liquid hammer force, and may also have the stretchability being able to follow the compression displacement of the elastic cushion K.
The above discussed elastic cushion K uses, as the material thereof, the elastic hollow spheres added type of silicone gel, comprising a silicone gel cushion K1 as the essential material of the elastic cushion K, and elastic hollow spheres K2 incorporated in the silicone gel cushion K1.
However, when the elastic hollow spheres added type of silicone gel discussed above repeatedly absorbs the liquid hammer force for a long period of time, the contact surface between the elastic hollow sphere K2 and the silicone gel cushion K1 would collapse or exfoliate, consequently it has been found that the long-term liquid hammer absorption effect cannot be guaranteed according to the above liquid hammer prevention device 700. This is so-called xe2x80x9csofteningxe2x80x9d of the elastic hollow sphere added type of silicone gel, which softens the elastic hollow sphere added type of silicone gel when an external forth exceeding the predetermined amount is continuously applied to that silicone gel.
This softening would spread even to portion where the displacement of the elastic hollow sphere added type of silicone gel becomes in contact with the casing K0 due to liquid hammer force. Consequently, the softening would cause the so-called xe2x80x9cbottom thrustxe2x80x9d in which the liquid hammer absorption function cannot be guaranteed, thereby the pressure energy conversion efficiency would be seriously reduced due to decrease of modulus of impact resilience.
The bottom thrust has been supposed to occur because of the softening of the whole body of elastic cushion due to multiple-stage factor. First, because of continuous compression displacement of the elastic hollow spheres K2, there occurs the exfoliation of elastic hollow spheres K2 out of the portion at which the silicone resin has been in contact with the elastic hollow spheres K2. Then, the exfoliation brings about the deterioration of external force transmission to the elastic hollow spheres K2, which eventually causes the softening of the whole body of the elastic cushion. Therefore, when using the silicone gel cushion K1, it has been necessary to secure the sufficient volume more than the predetermined amount, and the sufficient height allowing the compression displacement by the predetermined amount.
FIGS. 28 and 29 illustrate typical embodiments of the inner flange type of liquid hammer prevention device. A liquid hammer prevention device 800 of FIG. 28 is attached to any intermediate position of piping by means of a branch connection. The liquid hammer prevention device 800 has a main body 803 of which thread portion 803A is engaged with a thread portion 805B of a mounting ring 805, and the main body 803 is eventually led to a fluid channel through a passage hole 801, by means of engagement of a thread portion 805A of the mounting ring 805 with the fluid channel. A casing K0 is attached to and covers the outer periphery of the mounting ring 805 by engagement of a thread portion 805C of the mounting ring 805 with a thread portion 807 of the casing K0. There is formed an engagement groove 803E at the space between the mounting ring 805 and a head 803D of the main body 803 being inserted and placed inside the casing K0. A diaphragm C has an engagement protrusive portion C1 formed at the opening of diaphragm C and inwardly protruding in the radius direction thereof, and this engagement protrusive portion C1 is engaged with the engagement groove 803E. Thus the diaphragm C partitions the space inside the casing K0 into two areas, that is, an area S801 led to the fluid channel via the passage hole 801, and an area S802 provided for an elastic cushion 809 incorporated in the casing K0. The tightness of sealing of fluid between the areas S801 and S802 is maintained by means of the engagement protrusive portion C1 being caught toward the axis X by two elements, that is the head 803D and the mounting ring 805, on account of engagement of the thread portion 803A with the thread portion 805B.
Further, FIG. 29 illustrates another type of liquid hammer prevention device 900. This liquid hammer prevention device 900 is in a form of faucet handle, in which a water hammer arrestor unit is incorporated. In particular, the liquid hammer prevention device 900 is provided inside a handle 919 which controls open/close of a spindle 911. The spindle 911 comprises a thread portion 911A being engaged with an accepting female thread portion of a valve main body (not shown) and a valve element 913 positioned below. There is a passage hole 901 penetrating through the axis X of the spindle 911, and a thread portion of a main body 903 is in engagement with an accepting thread portion of the spindle 911 at the top thereof so that the fluid may not leak out of the space between the spindle 911 and the main body 903. The other structure is substantially the same as that of the liquid hammer prevention device 800. That is, there is a mounting ring 905 of which thread portion being engaged with an accepting thread portion 903N provided at an outer periphery 903B of the main body 903, and a casing K0 serving as the handle 919 is attached to and covers the mounting ring 905 by engagement of a thread portion 905C of the mounting ring 905 with an accepting thread portion 907 of the casing K0.
There is formed an engagement groove 903E at the space between the mounting ring 905 and a head 903D of the main body 903 being inserted and placed inside the casing K0. A diaphragm C has an engagement protrusive portion C1 formed at the opening of diaphragm C and inwardly protruding in the radius direction thereof, and this engagement protrusive portion C1 is engaged with the engagement groove 903E. Thus the diaphragm C partitions the space inside the casing K0 into two areas, that is, an area S901 led to the fluid channel via the passage hole 901, and an area S902 provided for an elastic cushion 909 incorporated in the casing K0. The tightness of sealing of fluid between the areas S901 and S902 is maintained by means of the engagement protrusive portion C1 being caught toward the axis X by two elements, that is the head 903D and the mounting ring 905, on account of engagement of the thread portion 903N with the thread portion 905B.
The inner flange type of liquid hammer prevention device as above discussed is required to secure the performance that the elastic cushion material can maintain the liquid hammer prevention function for a long time, and to secure the sufficient tightness of liquid sealing of the diaphragm so that the fluid may not leak out of the connecting part between the diaphragm and the casing, which would cause intrusion of fluid into the casing space incorporating the elastic cushion. If the fluid leaks and intrudes into the inner space of the casing, the elastic cushion will become put in the fluid, in other words, the elastic cushion will become floating in the fluid. Eventually, the liquid hammer force is received by the whole surface of the elastic cushion at the same time, thus the effective energy conversion cannot be carried out. Further, when the fluid intrudes into the space between the elastic cushion and the diaphragm and thereby the layer of fluid is formed, the pressure energy of liquid hammer cannot be transmitted to the elastic cushion effectively, thus the effective energy conversion cannot be carried out, and also the effective absorption and reduction of the liquid hammer cannot be carried out. In addition, the prevention of leakage of fluid out of the casing is also required in order to maintain the good condition of the device itself.
The fastening of the diaphragm in order to secure the tightness of fluid sealing of the liquid hammer prevention device as above discussed is carried out by fastening the thread between the mounting ring and the head of the main body. This causes the increase of number of parts as well as the number of working or assembly steps. Consequently, there arises the economic problem that the production cost of liquid hammer prevention device would become higher, and also the technical problem that the stable product quality cannot be maintained due to unevenness of the fastening force might be applied to the thread parts during assembly of the liquid hammer prevention device.
Therefore, the inventors focused on the problems arisen from the conventional type of liquid hammer prevention device as above discussed. It is a first object of the present invention to provide a liquid hammer prevention device which may effectively maintain the liquid hammer prevention function for a long time. Further, it is a second object of the present invention to provide a liquid hammer prevention device which, in addition to the first object of the present invention to effectively maintain the liquid hammer prevention function for a long time, is provided with the superior performance of liquid sealing tightness, as well as with the simple maintenance structure, so that the stable product quality and the lower production cost may be accomplished.
To achieve the objects mentioned above, according to claim 1 of the present invention, there is provided a liquid hammer prevention device comprising a casing led to a fluid channel via passage hole; an elastic cushion incorporated in the casing; and a diaphragm partitioning the inside of the casing into an area led to the fluid channel and another area incorporating the elastic cushion, wherein the elastic cushion is a foamed material of which initial hardness is xe2x80x9cAsker C 30-85xe2x80x9d according to JIS (Japanese Industrial Standard) S 6050 measured by the level gauge of a durometer xe2x80x9cAsker Cxe2x80x9d manufactured by Kobunshi Keiki Co., Ltd. of Kyoto, Japan (hereinafter referred to as xe2x80x9cAsker Cxe2x80x9d), and of which apparent specific gravity is 0.30-0.70.
According to claim 2 of the present invention, there is provided a liquid hammer prevention device comprising: a casing led to a fluid channel via passage hole; an elastic cushion incorporated in the casing; and a diaphragm partitioning the inside of the casing into an area led to the fluid channel and another area incorporating the elastic cushion, wherein the elastic cushion is a foamed material of which initial hardness is xe2x80x9cAsker C 50-85,xe2x80x9d and of which apparent specific gravity is 0.30-0.40.
According to claim 3 of the present invention, there is provided a liquid hammer prevention device comprising: a casing led to a fluid channel via passage hole; an elastic cushion incorporated in the casing; and a diaphragm partitioning the inside of the casing into an area led to the fluid channel and another area incorporating the elastic cushion, wherein the elastic cushion is a foamed material of which initial hardness is xe2x80x9cAsker C 55-70,xe2x80x9d and of which apparent specific gravity is 0.30-0.40.
According to claim 4 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 1, wherein, the elastic cushion is a low-profile shape having small height and large diameter; the diaphragm is in a flat plate shape of which diameter being larger than the diameter of the elastic cushion; and an outer rim of the diaphragm is supported by an inner wall of the casing.
According to claim 5 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 2, wherein, the elastic cushion is a low-profile shape having small height and large diameter; the diaphragm is in a flat plate shape of which diameter being larger than the diameter of the elastic cushion; and an outer rim of the diaphragm is supported by an inner wall of the casing.
According to claim 6 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 3, wherein, the elastic cushion is a low-profile shape having small height and large diameter; the diaphragm is in a flat plate shape of which diameter being larger than the diameter of the elastic cushion; and an outer rim of the diaphragm is supported by an inner wall of the casing.
According to claim 7 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 1, comprising: a casing; an elastic cushion incorporated in the casing; a main body positioned inside the casing and having a passage hole led to a fluid channel; and a diaphragm having at the opening rim an engagement protrusive portion protruding in the inward radius direction and being engaged with an engagement groove formed at a head of the main body, thereby the engagement protrusive portion being secured to and fixed on the engagement groove and an inner wall of the casing, wherein, the diaphragm is provided with a protrusive portion protruding in the outward radius direction of which width in the radius direction between an inner peripheral surface and an outer peripheral surface of the engagement protrusive portion being not less than the width in the radius direction between a side wall peripheral surface and the inner wall of the casing.
According to claim 8 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 2, comprising: a casing; an elastic cushion incorporated in the casing; a main body positioned inside the casing and having a passage hole led to a fluid channel; and a diaphragm having at the opening rim an engagement protrusive portion protruding in the inward radius direction and being engaged with an engagement groove formed at a head of the main body, thereby the engagement protrusive portion being secured to and fixed on the engagement groove and an inner wall of the casing, wherein, the diaphragm is provided with a protrusive portion protruding in the outward radius direction of which width in the radius direction between an inner peripheral surface and an outer peripheral surface of the engagement protrusive portion being not less than the width in the radius direction between a side wall peripheral surface and the inner wall of the casing.
According to claim 9 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 3, comprising: a casing; an elastic cushion incorporated in the casing; a main body positioned inside the casing and having a passage hole led to a fluid channel; and a diaphragm having at the opening rim an engagement protrusive portion protruding in the inward radius direction and being engaged with an engagement groove formed at a head of the main body, thereby the engagement protrusive portion being secured to and fixed on the engagement groove and an inner wall of the casing, wherein, the diaphragm is provided with a protrusive portion protruding in the outward radius direction of which width in the radius direction between an inner peripheral surface and an outer peripheral surface of the engagement protrusive portion being not less than the width in the radius direction between a side wall peripheral surface and the inner wall of the casing.
According to claim 10 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 1, comprising: a casing; an elastic cushion incorporated in the casing; a main body positioned inside the casing and having a passage hole led to a fluid channel; and a diaphragm having at the opening rim an engagement protrusive portion protruding in the inward radius direction and being engaged with an engagement groove formed at a head of the main body, thereby the engagement protrusive portion being secured to and fixed on the engagement groove and an inner wall of the casing, wherein, the main body is provided on a side wall peripheral surface of the engagement groove with a projective portion projecting in the outward radius direction.
According to claim 11 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 2, comprising: a casing; an elastic cushion incorporated in the casing; a main body positioned inside the casing and having a passage hole led to a fluid channel; and a diaphragm having at the opening rim an engagement protrusive portion protruding in the inward radius direction and being engaged with an engagement groove formed at a head of the main body, thereby the engagement protrusive portion being secured to and fixed on the engagement groove and an inner wall of the casing, wherein, the main body is provided on a side wall peripheral surface of the engagement groove with a projective portion projecting in the outward radius direction.
According to claim 12 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 3, comprising: a casing; an elastic cushion incorporated in the casing; a main body positioned inside the casing and having a passage hole led to a fluid channel; and a diaphragm having at the opening rim an engagement protrusive portion protruding in the inward radius direction and being engaged with an engagement groove formed at a head of the main body, thereby the engagement protrusive portion being secured to and fixed on the engagement groove and an inner wall of the casing, wherein, the main body is provided on a side wall peripheral surface of the engagement groove with a projective portion projecting in the outward radius direction.
According to claim 13 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 1, comprising: a casing; an elastic cushion incorporated in the casing; a main body positioned inside the casing and having a passage hole led to a fluid channel; and a diaphragm having at the opening rim an engagement protrusive portion protruding in the inward radius direction and being engaged with an engagement groove formed at a head of the main body , thereby the engagement protrusive portion being secured to and fixed on the engagement groove and an inner wall of the casing, wherein, the diaphragm is provided with a protrusive portion protruding in the outward radius direction of which width in the radius direction between an inner peripheral surface and an outer peripheral surface of the engagement protrusive portion being not less than the width in the radius direction between a side wall peripheral surface and the inner wall of the casing, and the main body is provided on a side wall peripheral surface of the engagement groove with a projective portion projecting in the outward radius direction.
According to claim 14 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 2, comprising: a casing; an elastic cushion incorporated in the casing; a main body positioned inside the casing and having a passage hole led to a fluid channel; and a diaphragm having at the opening rim an engagement protrusive portion protruding in the inward radius direction and being engaged with an engagement groove formed at a head of the main body, thereby the engagement protrusive portion being secured to and fixed on the engagement groove and an inner wall of the casing, wherein, the diaphragm is provided with a protrusive portion protruding in the outward radius direction of which width in the radius direction between an inner peripheral surface and an outer peripheral surface of the engagement protrusive portion being not less than the width in the radius direction between a side wall peripheral surface and the inner wall of the casing, and the main body is provided on a side wall peripheral surface of the engagement groove with a projective portion projecting in the outward radius direction.
According to claim 15 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 3, comprising: a casing; an elastic cushion incorporated in the casing; a main body positioned inside the casing and having a passage hole led to a fluid channel; and a diaphragm having at the opening rim an engagement protrusive portion protruding in the inward radius direction and being engaged with an engagement groove formed at a head of the main body, thereby the engagement protrusive portion being secured to and fixed on the engagement groove and an inner wall of the casing, wherein, the diaphragm is provided with a protrusive portion protruding in the outward radius direction of which width in the radius direction between an inner peripheral surface and an outer peripheral surface of the engagement protrusive portion being not less than the width in the radius direction between a side wall peripheral surface and the inner wall of the casing, and the main body is provided on a side wall peripheral surface of the engagement groove with a projective portion projecting in the outward radius direction.
According to claim 16 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 7, wherein the diaphragm is provided at the bottom of the engagement protrusive portion with a thin lip portion protruding in the inward radius direction being in tight contact by liquid pressure function with a lower surface of the engagement groove.
According to claim 17 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 8, wherein the diaphragm is provided at the bottom of the engagement protrusive portion with a thin lip portion protruding in the inward radius direction being in tight contact by liquid pressure function with a lower surface of the engagement groove.
According to claim 18 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 9, wherein the diaphragm is provided at the bottom of the engagement protrusive portion with a thin lip portion protruding in the inward radius direction being in tight contact by liquid pressure function with a lower surface of the engagement groove.
According to claim 19 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 10, wherein the diaphragm is provided at the bottom of the engagement protrusive portion with a thin lip portion protruding in the inward radius direction being in tight contact by liquid pressure function with a lower surface of the engagement groove.
According to claim 20 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 11, wherein the diaphragm is provided at the bottom of the engagement protrusive portion with a thin lip portion protruding in the inward radius direction being in tight contact by liquid pressure function with a lower surface of the engagement groove.
According to claim 21 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 12, wherein the diaphragm is provided at the bottom of the engagement protrusive portion with a thin lip portion protruding in the inward radius direction being in tight contact by liquid pressure function with a lower surface of the engagement groove.
According to claim 22 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 13, wherein the diaphragm is provided at the bottom of the engagement protrusive portion with a thin lip portion protruding in the inward radius direction being in tight contact by liquid pressure function with a lower surface of the engagement groove.
According to claim 23 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 14, wherein the diaphragm is provided at the bottom of the engagement protrusive portion with a thin lip portion protruding in the inward radius direction being in tight contact by liquid pressure function with a lower surface of the engagement groove.
According to claim 24 of the present invention, there is provided the liquid hammer prevention device as claimed in claim 15, wherein the diaphragm is provided at the bottom of the engagement protrusive portion with a thin lip portion protruding in the inward radius direction being in tight contact by liquid pressure function with a lower surface of the engagement groove.
With this structure, according to the liquid hammer prevention device of claim 1, the elastic cushion is made of the foamed material of which initial hardness is xe2x80x9cAsker C 30-85xe2x80x9d and apparent specific gravity is 0.30-0.70. This elastic material has uncountable isolated fine cells, and can serve as the pressure energy conversion medium by securing the displacement amount from uncountable isolated fine elastic cells as well as by the energy loss due to the inner friction (viscoelasticity characteristic). Further, since the polyurethane elastomer is polymer, but not a composite of different materials and fillers, the hardness results from the molecular structure of the polymer, this material can be formulated and foamed at an arbitrary high-hardness level with excellent mechanical strength, damping properties, good durability because of good compression set and repeated compression characteristics. Consequently, this material may maintain the energy absorption and damping performance against the liquid hammer for a long time. Further, this material may be formed into any shape at will, which may contribute to the downsize of products.
According to the liquid hammer prevention device of claim 2, the elastic cushion is made of the foamed material of which initial hardness is xe2x80x9cAsker C 50-85xe2x80x9d and apparent specific gravity is 0.30-0.40. This elastic material can serve as the pressure energy conversion medium by securing the displacement amount from uncountable isolated fine elastic cells as well as by the energy loss due to the inner friction (viscoelasticity characteristic). Further, this material can be formulated and foamed at an arbitrary high-hardness level with excellent mechanical strength, damping properties, good durability because of good compression set and repeated compression characteristics. This material may maintain the energy absorption and damping performance against the liquid hammer for a long time even under the severe condition of high temperature and high pressure. Further, this material may be formed into any shape at will, which may contribute to the downsize of products.
According to the liquid hammer prevention device of claim 3, the elastic cushion is made of the foamed material of which initial hardness is xe2x80x9cAsker C 55-70xe2x80x9d and apparent specific gravity is 0.30-0.40. This elastic material can serve as the pressure energy conversion medium by securing the displacement amount from uncountable isolated fine elastic cells as well as by the energy loss due to the inner friction (viscoelasticity characteristic). Further, this material can be formulated and foamed at an arbitrary high-hardness level with excellent mechanical strength, damping properties, good durability because of good compression set and repeated compression characteristics. This material may maintain the energy absorption and damping performance against the liquid hammer for a long time even under the severe condition of high temperature and high pressure. Further, this material may be formed into any shape at will, which may contribute to the downsize of products.
According to the liquid hammer prevention device of claims 4 through 6, the foamed material as above discussed is adopted as the elastic cushion in low-profile and large-diameter, and the diaphragm is in the thin and flat plate shape of which diameter is larger than that of the elastic cushion. Thus the overall height of the elastic cushion and the diaphragm can be lowered. Consequently, the liquid hammer prevention device may become low-profile allowing the downsizing structure. Further, the liquid hammer prevention device may be easily installed in any narrow space of water or liquid related instruments.
According to the liquid hammer prevention device of claims 7 through 9, the engagement groove provided at the head of the main body positioned inside the casing is engaged with the engagement protrusive portion, formed at the opening rim of the diaphragm protruding in the inward radius direction. The diaphragm is fixed on and secured to the space between the casing and the main body, by engagement of the engagement protrusive portion with the engagement groove of the main body and with the inner wall of the casing. Thus the diaphragm partitions the space inside the casing into two areas, that is, the area led to the fluid channel via the passage hole, and the area provided for the elastic cushion incorporated in the casing. The engagement protrusive portion of the diaphragm has protrusive portions outwardly protruding in the radius direction, provided on an outer peripheral surface. The width in the radius direction between the inner peripheral surface and the outer peripheral surface of the engagement protrusive portion, is not less than the width in the radius direction between the side wall peripheral surface of the engagement groove and the inner wall of the casing. Consequently, the outer peripheral surface of the engagement protrusive portion is pressed by the inner wall of the casing, thereby the engagement protrusive portion is deformed expanding both in the inward radius direction and the outward radius direction. Further, both the top and the bottom of the engagement protrusive portion are also deformed expanding in the axial direction. Accordingly, the inner peripheral surface of the engagement protrusive portion is pressed by the side wall peripheral surface of the engagement groove, thereby each of the areas is tightly sealed.
With this structure, there is no possibility of intrusion of fluid, from the area led to the fluid channel via the passage hole, into the other area inside the casing in which the elastic cushion is incorporated, thus the floating of elastic cushion in the fluid, or the situation of not being able to efficiently convert the energy due to generation of layer of liquid between the elastic cushion and the diaphragm will not occur, so the excellent performance serving as the liquid hammer prevention device can be maintained for a long time. Further, there is no possibility of leakage of fluid out of the casing, so the good condition of the device itself can be maintained. The engagement groove provided at the head of the main body is engaged with the engagement protrusive portion, formed at the opening rim of the diaphragm protruding in the inward radius direction. In addition, the diaphragm is fixed on and secured to the space between the casing and the main body, by engagement of the engagement protrusive portion with the engagement groove of the main body, and with the inner wall of the casing. Therefore, the liquid hammer prevention device according to the present invention requires less number of assembly parts as well as less number of assembly working steps. So the liquid hammer prevention device may be manufactured at the lower cost, maintaining the uniformity of product quality at the same time.
According to the liquid hammer prevention device of claims 10 through 12, the engagement groove provided at the head of the main body inserted in the casing is engaged with the engagement protrusive portion, formed at the opening rim of the diaphragm protruding in the inward radius direction. Thus the diaphragm partitions the space inside the casing into two areas, that is, the area led to the fluid channel via the passage hole, and the area provided for the elastic cushion incorporated in the casing. The protrusive portions provided on the side wall peripheral surface of the engagement groove is caught and incorporated by the inner peripheral surface of the engagement protrusive portion of the diaphragm, thereby the engagement protrusive portion of the diaphragm is deformed expanding in the radius direction and in the axial direction. Accordingly, the outer peripheral surface of the engagement protrusive portion is pressed by the side wall of the casing, and the inner peripheral surface of the engagement protrusive portion is strongly pressed by the protrusive portions by the reaction force. Further, both the top and the bottom of the engagement protrusive portion are also deformed expanding in the axial direction, thereby each of the areas is tightly sealed.
With this structure, there is no possibility of intrusion of fluid, from the area led to the fluid channel via the passage hole, into the other area inside the casing in which the elastic cushion is incorporated, thus the floating of elastic cushion in the fluid, or the situation of not being able to efficiently convert the energy due to generation of layer of liquid between the elastic cushion and the diaphragm will not occur, so the excellent performance serving as the liquid hammer prevention device can be maintained for a long time. Further, there is no possibility of leakage of fluid out of the casing, so the good condition of the device itself can be maintained. The engagement groove provided at the head of the main body is engaged with the engagement protrusive portion, formed at the opening rim of the diaphragm protruding in the inward radius direction. In addition, the diaphragm is fixed on and secured to the space between the casing and the main body, by engagement of the engagement protrusive portion with the engagement groove of the main body, and with the inner wall of the casing. Therefore, the liquid hammer prevention device according to the present invention requires less number of assembly parts as well as less number of assembly working steps. So the liquid hammer prevention device may be manufactured at the lower cost, maintaining the uniformity of product quality at the same time.
According to the liquid hammer prevention device of claims 13 through 15, the engagement groove provided at the head of the main body positioned inside the casing is engaged with the engagement protrusive portion, formed at the opening rim of the diaphragm protruding in the inward radius direction. The diaphragm is fixed on and secured to the space between the casing and the main body, by engagement of the engagement protrusive portion with the engagement groove of the main body and with the inner wall of the casing. Thus the diaphragm partitions the space inside the casing into two areas, that is, the area led to the fluid channel via the passage hole, and the area provided for the elastic cushion incorporated in the casing. The width in the radius direction between the inner peripheral surface and the outer peripheral surface of the engagement protrusive portion is not less than the width in the radius direction between the side wall peripheral surface of the engagement groove and the inner wall of the casing. Consequently, the outer peripheral surface of the engagement protrusive portion is pressed by the inner wall of the casing, thereby the engagement protrusive portion is deformed expanding both in the inward and outward radius directions, and the inner peripheral surface of the engagement protrusive portion is pressed by the outer peripheral surface of the engagement groove. Further, the protrusive portions are caught by the inner peripheral surface of the engagement protrusive surface, thus the engagement protrusive portion is further deformed expanding in the radius and axial directions. Accordingly, the outer peripheral surface of the engagement protrusive portion is strongly pressed by the inner wall of the casing, and because of the reaction force generated thereby, the inner peripheral surface of the engagement protrusive portion is strongly pressed by the protrusive portions, thereby each of the areas is tightly sealed.
With this structure, there is no possibility of intrusion of fluid, from the area led to the fluid channel via the passage hole, into the other area inside the casing in which the elastic cushion is incorporated, thus the floating of elastic cushion in the fluid, or the situation of not being able to efficiently convert the energy due to generation of layer of liquid between the elastic cushion and the diaphragm will not occur, so the excellent performance serving as the liquid hammer prevention device can be maintained for a long time. Further, there is no possibility of leakage of fluid out of the casing, so the good condition of the device itself can be maintained. The engagement groove provided at the head of the main body is engaged with the engagement protrusive portion, formed at the opening rim of the diaphragm protruding in the inward radius direction. In addition, the diaphragm is fixed on and secured to the space between the casing and the main body, by engagement of the engagement protrusive portion with the engagement groove of the main body, and with the inner wall of the casing. Therefore, the liquid hammer prevention device according to the present invention requires less number of assembly parts as well as less number of assembly working steps. So the liquid hammer prevention device may be manufactured at the lower cost, maintaining the uniformity of product quality at the same time.
According to the liquid hammer prevention device of claims 16 through 24, there is the thin lip portion formed in the inward radius direction at the lower part of the engagement protrusive portion. If by some accident the liquid intrudes into the engagement groove, since the lip portion becomes in close contact with the lower portion of the engagement groove due to the force in the direction of liquid pressure, the tight liquid sealing performance is accomplished.
With this structure, there is no possibility of intrusion of fluid, from the area led to the fluid channel via the passage hole, into the other area inside the casing in which the elastic cushion is incorporated, thus the floating of elastic cushion in the fluid, or the situation of not being able to efficiently convert the energy due to generation of layer of liquid between the elastic cushion and the diaphragm will not occur, so the excellent performance serving as the liquid hammer prevention device can be maintained for a long time. Further, there is no possibility of leakage of fluid out of the casing, so the good condition of the device itself can be maintained. The engagement groove provided at the head of the main body is engaged with the engagement protrusive portion, formed at the opening rim of the diaphragm protruding in the inward radius direction. In addition, the diaphragm is fixed on and secured to the space between the casing and the main body, by engagement of the engagement protrusive portion with the engagement groove of the main body, and with the inner wall of the casing. Therefore, the liquid hammer prevention device according to the present invention requires less number of assembly parts as well as less number of assembly working steps. So the liquid hammer prevention device may be manufactured at the lower cost, maintaining the uniformity of product quality at the same time.